Distillate



h3, 1964 R. M. SKOMOROSKI ETAL 3,123,550

HYDROTREATING OF MINERAL on DISTILLATES Filed June 20, 1960 'DISTILLATE MIXING ACID HYDROGEN 3 e FEED 4, 7 A7 HYDROGENATION J EN ZONE RECYCLE 5 DISTILLATE 8x SCRUBBER RECYCLE I 2 IO 1 GAS SEPARATOR PURSE WATER WASH CAUSTIC WASH RESIDUAL TREATED WATER 1 SEPARATOR i 0| STILLATE Robert M. Skomoroski Alcm Schriesheim Inventors Pate M Attorney United States Patent 3,123,559 HYDROTREATING 0F MINERAL OIL DISTILLATES Robert M. Skomoroski, Elizabeth, and Alan Schn'esheim,

Berkeley Heights, N.J., assignors to Esso Research and Engineering Company, a corporation of Delaware Filed dune 2.0, 1969, Ser. No. 37,489 6 Claims. (Cl. 208-454) The present invention relates to a process for hydrogenating oil-soluble nitrogenous compounds found as contaminants in mineral oil distillates. More particularly, the invention concerns a process for removing nitrogen from hydrocarbon distillates boiling above about 200 F., especially shale oil distillates, by hydrotreating an admixture of the distillate and a mineral acid over a supported hydrogenation catalyst.

The existence of oil-soluble nitrogen-containing compounds in crude mineral oils is well known, as is the fact that the hydrocarbon distillates of these oils also are contaminated with nitrogenous compounds. While the chemical structures of these nitrogen contaminants is not with certainty known, analyses indicate that much of the nitrogen is present in the form of amines or nitrogen bases, especially in those distillates boiling above about 350 F. These include pyridine, quinoline, alkylated derivatives thereof, and more highly condensed aromatic nitrogen compounds. Regardless of their structures, however, the presence of these nitrogen contaminants is undesirable, for they not only impart odor, poor color, and instability to the distillates, but also have severely adverse effects on such catalytic processes as cracking, isomerization, reforming, and other refining operations by which the distillates are converted into more useful products. Especially is this so with shale oil distillates which are produced by heating and retorting shale rock such as that which is found in Colorado and elsewhere, and which may contain as high as 4 weight percent nitrogen.

It has now been found that if the mineral oil distillate is admixed with mineral acid and the acidified admixture subjected to hydrotreating in the presence of a hydrogenation catalyst, removal of nitrogenous contaminants is surprisingly accomplished at less severe conditions than found necessary in the hydrotreating processes heretofore utilized. The removal of sulfur-containing compounds, also generally present as contaminants in mineral oil distillates, is at the same time fiacilitated by the use of acidified admixtures. While the manner in which the presence of said operates to effect these desirable results is not with certainty known, it is believed that the acid protons complex with the basic centers in the distillate, thereby decreasing the tendency of the basic components to be adsorbed on the active surfaces of the catalyst. The acids may additionally complex with the suliurous materials which are known to be strong catalyst poisons. As a consequence, additional catalyst surface is available for hydrogen adsorption, thus increasing the concentration of available active hydrogen and speeding up the rate of the hydrotreating reactions.

The process of the present invention generally comprises admixing a nitrogen-containing mineral oil distillate with a mineral acid, and subjecting the admixture to hydrotreating conditions in the presence of a hydrogenation catalyst. Referring to the figure, which illustrates a flow diagram of the process, mineral oil distillate and mineral acid are fed through lines 1 and 2, respectively, to a mixing zone 3 Where they are admixed by any suitable means such as by stirring devices, orifice mixers, or by withdrawing liquid from the bottom of the mixing zone and ice pumping it to the top of the mixing zone. The acid admixture is then passed through line 4 into a hydrogenaion zone 5. Alternatively, the mineral acid may be admitted directly to the hydrogenation zone through line 6, and there admixed with the distillate. An excess of hydrogen gas generally 300 to 1200 s.c.f. per barrel of dis tillate is admitted to the hydrogenation zone through line 7. The acid admixture and the hydrogen are intimately contacted in the hydrogenation zone with a hydrogenation catalyst bed, which may be of the fixed, moving or fluidized type, under hydrotreating conditions such that the nitrogen is converted to ammonia. The efiluent from the hydrogenation zone passes through line 8 into a gas separator 9, from which excess hydrogen is purged through line 12 or recycled through line 10 and scrubber 11 wherein ammonia and hydrogen sulfide are removed. The acid and distillate admixture is removed from the gas separator through line 13 and passed into a water wash zone 14. The water-washed distillate is then passed through line 15 into a caustic wash zone 16; optionally, part of the water-washed distillate may be recycled through line 17 to provide a diluent feed to the hydrogenation zone, thereby providing means for controlling the temperature of the exothermic hydrogentreating step. The effluent from the caustic wash zone is passed through line 13 into a separator zone 19 wherein the distillate is separated from any residual water. The distillate from the separator may be utilized directly or processed further in other refining operations wherein a treated distillate stream of reduced nitrogen content is desirable.

While the process is generally applicable to any essentially hydrocarbon distillate such as derived from either crude petroleum or oil-bearing shales, it is particularly useful in removing nitrogenous contaminants from distillates boiling in the range of about 200 F. to about 1050 F, e.g., distillates in the naphtha, lubricating oil and heating oil boiling ranges. The process is especially useful in treating distillates obtained from oil-bearing shales; typical physical properties of such a distillate are:

TABLE I Boiling range, F 350-1000 A.P.I. gravity 15.025.0 C/H ratio 5-8 Av. mol. wt. (3 225-325 Nitrogen, wt. percent 0.5-4.0 Sulfur, wt. percent 0.3-3.0

L The acid with which the distillate is admixed prior to the hydrogenation treating step of the process may be any mineral acid, e.g., acids such as the hydrohalides, sulfuric acid, phosphoric acid, nitric acid, etc. It is preferable to utilize an acid which forms homogeneous solutions with the hydrocarbon feed, although this is not absolutely essential. In general, the strong inorganic acids are to be preferred, sulfuric acid being most preferred where the hydrotreating step is carried out in predominantly liquid phase, whereas the hydrohalides are preferred for predominantly vapor phase processes.

In order to realize the advantages of the present invention, the amount of acid admixed with the distillate must be sufiicient to give at least a 1:1 gram equivalent ratio of acid hydrogen to basic center, i.e., nitrogen, in the feed. For example, a minimum amount of at least 0.5 mole of sulfuric acid, 1 mole of hydrogen halide, or 0.33 mole of phosphoric acid must be provided for each gram atom of nitrogen in the feed. The minimum Where A=parts by weight acid per 100 parts distillate,

N=Weight percent nitrogen in the distillate,

M=rnolecular Weight of acid,

P number of hydrogen ions formed upon complete ionization of acid.

While the minimum amount of acid facilitates the removal of the nitrogen contaminants from the distillate feed in accordance with the present invention, it is preferable to use an excess of acid, generally from 2 to times the amount calculated by the above formula, i.e., a 2 to 5/1 gram equivalent ratio of acid hydrogen to basic center in the feed.

The hydrogenation catalyst utilized in the process may be any of the well-known hydrogenation catalysts. However, it is preferred that the catalyst contain as the active ingredient a metal of the group platinum, palladium, ruthenium, osmium, cobalt and nickel. Catalysts containing platinum, palladium or ruthenium are especially preferred because of their greater activity. While unsupported catalysts may be utilized, supported catalysts especially of the type wherein the carrier is a porous substance such as alumina, silica, silica-alumina, etc., are more advantageously employed in the present process. Supported catalysts of the preferred type, e.g., platinum on alumina, can be prepared as described in U.S. Patent No. 2,895,905; however, any of the other well-known methods of preparing supported hydrogenation catalysts may be utilized.

The hydrotreating step of the invention can be carried out in either vapor or liquid phase under hydrotreating conditions as set forth in the following table:

TABLE II Hydrotreating Conditions The invention is further described and illustrated by the following examples.

EXAMPLE 1 A Colorado shale oil distillate containing 2.07 weight percent nitrogen and 0.77 weight percent sulfur, initial boiling point 370 F., 50% overhead at 699 F., 21.0 A.P.I. gravity, is admixed with 2 moles of commercial sulfuric acid (96.6 Weight percent H 80 per gram atom of nitrogen in the distillate. The acid-distillate admixture is then hydrogenated under the specific conditions set forth in Table II over 1000 grams of an alumina-base platinum catalyst containing 0.6 weight percent platinum and prepared by impregnating an alcoholate-derived alumina gel with dilute aqueous chloroplatinic acid. The hydrogenated product is then washed with water and with caustic solution to remove acid. In this Way over 90% of the nitrogenous contaminants of the distillate feed are removed.

EXAMPLE 2 In a manner similar to that described in Example 1, the shale oil distillate and 1.5 moles of commercial phosphoric acid (86.4 Weight percent H PO per gram atom of nitrogen in the distillate are admixed and hydrotreated over a palladium oxide catalyst containing 3 weight percent palladium on a silica gel base. The nitrogen contamination of the distillate is reduced in this manner by about EXALIPLE 3 A heating oil derived from heavy catalytic cracked stock and containing about 65 weight percent paraflins and naphthenes and about 35 weight percent aromatics, and having an ASTM boiling range of about 300 F. to about 650 F., a nitrogen content of about 0.05 Weight percent and a sulfur content of about 0.4 weight percent is admixed with 2 moles of anhydrous hydrogen chloride gas per gram atom of nitrogen in the oil. The admixture is then passed at a rate of 5 v./v./hr. under a hydrogen partial pressure of 400 p.s.i.g. over a Raney nickel catalyst at 400 F. The sulfur content of the hydrogenated product is reduced to a negligible amount and over of the nitrogenous contaminants are removed by the hydrotreatment.

EXAMPLE 4 By following the procedure of Example 3 over 95% of the nitrogenous and sulfurous contaminants of the heating oil distillate are removed by conducting the hydrotreatment over a catalyst containing 3 weight percent ruthenium supported on a 15% silica85% alumina base.

The removal of nitrogenous and sulfurous contaminants from lubricant oil distillates is similarly facilitated by hydrotreating the distillates in admixture with mineral acids.

The foregoing description of the invention contains a limited number of embodiments. It will be understood that numerous variations are within the skill of the art and that the scope of the invention is to be limited only by the appended claims.

What is claimed is:

1. A process for removing oil soluble nitrogen-containing compounds from a mineral oil distillate which comprises admixing said distillate with mineral acid and hydrotreating the resulting acid-containing adnnxture Over a supported metal containing hydrogenation catalyst at a pressure of from 300 to 1,000 p.s.i.g. and wherein the gram equivalent ratio of acid hydrogen to basic center in said admixture is from 2:1 to 5:1.

2. A process according to claim 1 in which the distillate is a shale oil distillate having a boiling range of about 350 F. to 1,000 F. and containing from 0.5 to 4 weight percent nitrogen.

3. A process according to claim 1 in which the mineral acid is selected from the class consisting of hydrogen halides, sulfuric acid and phosphoric acid.

4. A process according to claim 1 in which the hydrogenation catalyst comprises an acidic support and a metal selected from the class consisting of platinum, palladium and ruthenium.

5. A process for removing nitrogenous contaminants from shale oil distillate which comprises admixing said distillate with an amount of mineral acid sufiicient to give a gram equivalent ratio of acid hydrogen to nitrogen in said shale oil distillate of at least 1:1, passing said admixture with an excess of hydrogen over a supported metal containing hydrogenation catalyst comprising platinum on alumina at a temperature of 200 to 800 F. at a pressure of from 400 to 800 p.s.i.g. so as to convert the nitrogenous contaminants of the shale oil distillate to ammonia, and separating an essentially nitrogen-free shale oil distillate from the hydrotreated admixture.

6. A process for treating mineral oil distillates to remove oil soluble nitrogen compounds therefrom which comprises contacting in a hydrogenation zone an intimate mixture of (l) a mineral oil distillate containing oil-soluble nitrogen compounds and boiling within the range of 200 F. to 1050 F., (2) an amount of a min- 5 eral acid about 2 to 5 times that calculated from the formula wherein A equals parts by weight of mineral acid per 100 parts of distillate, N is the Weight percent of nitrogen in said distillate, M is the molecular weight of said acid and P the number of hydrogen ions formed upon complete ionization of said acid, and (3) from 300 to 1200 s.c.f. of hydrogen gas per barrel of distillate with a supported metal containing hydrogenation catalyst at a temperature between 400 F. and 600 F. and at pressures within the range of 400 to 800 p.s.i.g. for a time sufficient to convert the nitrogen of the oil-soluble nitrogen compounds contained in said distillate to ammonia,

separating the thus treated mixture of distillate, acid and References Cited in the file of this patent UNITED STATES PATENTS 2,704,758 Wetzel Mar. 22, 1955 2,786,121 Denton et a1 Oct. 23, 1956 2,966,450 Kimberlin et al. Dec. 27, 1960 2,984,617 De Chellis et a1 May 16, 1961 

1. A PROCESS FOR REMOVING OIL SOLUBLE NITROGEN-CONTAINING COMPOUNDS FROM A MINERAL OIL DISTILLATE WHICH COMPRISES ADMIXING SAID DISTILLATE WITH MINERAL ACID AND HYDROTRATING THE RESULTING ACID-CONTAINING ADMIXTURE OVER A SUPPORTED METAL CONTAINING HYDROGENATION CATALYST AT A PRESSURE OF FROM 300 1,000 P.S.I.G. AND WHEREIN THE GRAM EQUIVALENT RATIO OF ACID HYDROGEN TO BASIC CENTER IN SAID ADMIXTURE IS FROM 2:1 TO 5:1. 